Practical #5 Testing The Chemical Durability Of Glass Submitted By: Submitted To:
Dr.M.Ahmed Tindyala 2007-Met-
Practical #5 Testing The Chemical Durability Of Glass Introduction/Objectives: Chemical durability is resistance to change in size shape structure and chemical make up of glass Glasses have good corrosion resistance, therefore mostly use in storage containers Theory: Glass is uniformly reacted from surface by ion exchange method. Glass is attacked frim a corrosion reaction and for further reaction diffusion should take place. For example in factories HF in fumes bad the appefarance of glasses but these fumes don't react with steel, therefore a good quality glass is choosen for industrial purposes. According to ion exchange method when liquid react with glasses, Na ions are replaced by hydronium ions so NaOH is formed on surface and also SiOH is also formed next to the NaOH layer. NiOH look like gel. H-OH -> OH + H H + H2O -> H3O Na+OH -> NaOH
Depletion of Glass: Following steps are involve during the depletion of glass Leaching: It is profential extraction of metal or materials. Here replacement of Na ions is done by hydronium ions. Dissolution: SiOH formation on surface of glass under the NaOH layer and SiOH which is gel like is separated from glass surface. Congruent Dissolution: The Na ions which are replaced again taken by glass and an equillibrium is set up b/w the depletion and the again taken up of the Na ions. Glass forming controlling factors: Rate of glass forming controlling factors are fluxes temperature change Apparatus: weight balance, filter paper, oven, glass, water beaker, burner Pocedure: I took 30 gm of soda lime glass and crushed to -20 to +60 mesh Heated 250 ml water in 500 ml beaker to 90 0C Dissoled the cullet into boiling water and hold it for 30min Now I filtered the mixture The filtered glass along with the filte paper dried in an oven at 110 oC Weighted the glass to calculate the weight loss Observations and calculations: weight of cullet =.3 gm weight of cullet + weight of filter paper after test = weight loss = % weight loss = = Result: Weight loss =
Applications: Depending upon the type of atmosphere, the quality of glass is important. Glasses are used for various purposes, some are given below window glass refractory glass laboratory equipments,etc Comments:
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Reference: 07met.tk